In a prior filed patent application, issued as U.S. Pat. No. 4,930,764, whose contents are hereby incorporated by reference, a front end feeder for a high speed machine for handling mixed mail is described. The front feeder comprises a hopper region with a deck which is flat and in which is embedded a series of drive wheels which are angled toward a rear registration wall. The deck is angled slightly backwards and slightly towards the registration wall. When a stack of envelopes intended to be sealed and posted in this machine are loaded into the hopper, the function of the front feeder is to pre-shingle the mail while moving it downstream toward a singulator located downstream of the hopper. It is important that the envelopes be maintained in registration with this rear registration wall as they approach and enter the singulator.
While the mechanism described in this earlier patent performs extremely well in connection with average mail sizes, it has been found that on occasion, from time to time, very wide mail also known as flats tend to become misregistered. In other words, the very wide mail tend not to be maintained in registration with the rear registration wall as the envelopes are moved in a downstream direction towards the singulator.